/* 
 * Copyright (c) 2004-2008 QOS.ch
 * All rights reserved.
 * 
 * Permission is hereby granted, free  of charge, to any person obtaining
 * a  copy  of this  software  and  associated  documentation files  (the
 * "Software"), to  deal in  the Software without  restriction, including
 * without limitation  the rights to  use, copy, modify,  merge, publish,
 * distribute,  sublicense, and/or sell  copies of  the Software,  and to
 * permit persons to whom the Software  is furnished to do so, subject to
 * the following conditions:
 * 
 * The  above  copyright  notice  and  this permission  notice  shall  be
 * included in all copies or substantial portions of the Software.
 * 
 * THE  SOFTWARE IS  PROVIDED  "AS  IS", WITHOUT  WARRANTY  OF ANY  KIND,
 * EXPRESS OR  IMPLIED, INCLUDING  BUT NOT LIMITED  TO THE  WARRANTIES OF
 * MERCHANTABILITY,    FITNESS    FOR    A   PARTICULAR    PURPOSE    AND
 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
 * LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
 * OF CONTRACT, TORT OR OTHERWISE,  ARISING FROM, OUT OF OR IN CONNECTION
 * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 */
package org.slf4j.helpers;

import org.slf4j.spi.MDCAdapter;

import java.util.HashMap;
import java.util.Map;
import java.util.Set;

/**
 * Basic MDC implementation, which can be used with logging systems that lack
 * out-of-the-box MDC support.
 *
 * This code is largely based on logback's <a
 * href="http://svn.qos.ch/viewvc/logback/trunk/logback-classic/src/main/java/org/slf4j/impl/LogbackMDCAdapter.java">
 * LogbackMDCAdapter</a>.
 *
 * @author Ceki Gulcu
 * @author Maarten Bosteels
 *
 * @since 1.5.0
 */
public class BasicMDCAdapter implements MDCAdapter {

    private InheritableThreadLocal inheritableThreadLocal = new InheritableThreadLocal();

    /**
     * Put a context value (the <code>val</code> parameter) as identified with
     * the <code>key</code> parameter into the current thread's context map.
     * Note that contrary to log4j, the <code>val</code> parameter can be null.
     *
     * <p>
     * If the current thread does not have a context map it is created as a side
     * effect of this call.
     *
     * @throws IllegalArgumentException in case the "key" parameter is null
     */
    public void put(String key, String val) {
        if (key == null) {
            throw new IllegalArgumentException("key cannot be null");
        }
        HashMap map = (HashMap) inheritableThreadLocal.get();
        if (map == null) {
            map = new HashMap();
            inheritableThreadLocal.set(map);
        }
        map.put(key, val);
    }

    /**
     * Get the context identified by the <code>key</code> parameter.
     */
    public String get(String key) {
        HashMap hashMap = (HashMap) inheritableThreadLocal.get();
        if ((hashMap != null) && (key != null)) {
            return (String) hashMap.get(key);
        } else {
            return null;
        }
    }

    /**
     * Remove the the context identified by the <code>key</code> parameter.
     */
    public void remove(String key) {
        HashMap map = (HashMap) inheritableThreadLocal.get();
        if (map != null) {
            map.remove(key);
        }
    }

    /**
     * Clear all entries in the MDC.
     */
    public void clear() {
        HashMap hashMap = (HashMap) inheritableThreadLocal.get();
        if (hashMap != null) {
            hashMap.clear();
            inheritableThreadLocal.remove();
        }
    }

    /**
     * Returns the keys in the MDC as a {@link Set} of {@link String}s The
     * returned value can be null.
     *
     * @return the keys in the MDC
     */
    public Set getKeys() {
        HashMap hashMap = (HashMap) inheritableThreadLocal.get();
        if (hashMap != null) {
            return hashMap.keySet();
        } else {
            return null;
        }
    }

    /**
     * Return a copy of the current thread's context map. Returned value may be
     * null.
     *
     */
    public Map getCopyOfContextMap() {
        HashMap hashMap = (HashMap) inheritableThreadLocal.get();
        if (hashMap != null) {
            return new HashMap(hashMap);
        } else {
            return null;
        }
    }

    public void setContextMap(Map contextMap) {
        HashMap hashMap = (HashMap) inheritableThreadLocal.get();
        if (hashMap != null) {
            hashMap.clear();
            hashMap.putAll(contextMap);
        } else {
            hashMap = new HashMap(contextMap);
            inheritableThreadLocal.set(hashMap);
        }
    }

}
